Method of assembling a seal device

ABSTRACT

A system for providing a seal between a housing and a shaft is formed of at least two ring members connected to each other by relative diametrical expansion with reduced or eliminated axial resilient deformation. The ring members may be held together by an annular protrusion located within a recess. To eliminate play between the protrusion and the recess, the device may be assembled by heating the recess and inserting the protrusion into the recess while the recess is expanded. The improved system can be accurately assembled, with the ring members located very close to each other. The system has improved oil retention and water exclusion properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for providing a seal between ashaft and a housing. In particular, the present invention relates to adynamic seal device for preventing lubricant from leaking out of ahousing and/or for preventing contaminants from traveling into thehousing. The present invention also relates to a method of assembling asealed system.

2. Description of the Related Art

Prior art devices for sealing a rotating shaft are disclosed in U.S.Pat. Nos. 4,022,479 (Orlowski) and 5,024,451 (Borowski). Seal devices ofthis type may be used to prevent lubricant from escaping out of abearing housing and/or to prevent contaminants from working their wayinto the housing. The prior art devices are formed of at least tworing-shaped members that rotate with respect to each other when theshaft is rotated. One of the members is fixed to the housing and doesnot rotate. The other member rotates with the rotating shaft.

The two ring members should be located very close together, particularlywhen the seal device is used to isolate the bearing from smallparticulate contaminants. Even small quantities of such contaminants arecapable of significantly deteriorating the bearing. To prevent suchcontamination, the two relatively rotatable ring members must be heldtogether very closely, with only a very narrow space therebetween.

The ring members of the Orlowski seal device are connected together by aseparate securing means, not shown in the prior art patent. The ringmembers themselves have no means for establishing and maintaining anarrow spacing therebetween. Therefore, the prior art seal device cannotbe manufactured as a unit with a preset, fixed spacing The spacingbetween the ring members has to be set when the seal device is installedinto the housing. This leaves room for human error outside the controlof the device manufacturer. In particular, the Orlowski device can beimproperly installed, with the ring members located too far apart toperform satisfactorily.

The ring members of the Borowski device are held together by a bead anda groove provided on the ring members themselves. The bead fits withinthe groove with an interference fit. This arrangement is an improvementover the Orlowski system in the sense that no separate securing means isneeded. But the Borowski device is still unsatisfactory because the beadmust be resiliently deformed to be positioned within the groove, and thegroove must be correspondingly enlarged to receive the deformed bead.The deformation of the bead during assembly makes it difficult toachieve the desired close positioning between the two ring members, asexplained in more detail below.

SUMMARY OF THE INVENTION

The disadvantages of the prior art are alleviated to a great extent bythe present invention which provides a seal device including first andsecond ring members having connecting portions, with the connectingportion of the second ring member being located radially inside of thefirst ring member, and with the connecting portions being connected toeach other by expansion of the first ring member relative to the secondring member.

In one aspect of the present invention, the connecting portions areconnected to each other by heat-induced expansion of the first ringmember.

In another aspect of the invention, the connecting portion of the firstring member is in the form of an annular recess, and the otherconnecting portion is an annular protrusion located within the recess.

In another aspect of the present invention, the seal device includes athird ring member for sealing the surface of a rotating shaft.

An object of the present invention is to provide a seal device that canbe accurately assembled, with very little play.

Another object of the invention is to provide a high performance sealdevice that can be produced economically.

Another object of the present invention is to provide an improved methodof assembling a seal device.

Other objects and advantages of the present invention will becomeapparent from the following description and drawings which illustratepreferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a seal device constructed inaccordance with a first embodiment of the present invention.

FIG. 2 is a partial cross sectional side view of the seal device of FIG.1, taken along line 2--2 of FIG. 1.

FIG. 3 is a partial cross sectional side view like FIG. 2, but showingthe seal device employed within a sealed system.

FIG. 4 is a rear elevational view of the stator member for the sealdevice of FIG. 1.

FIG. 5 is a bottom view of the seal device of FIG. 1.

FIG. 6 is an enlarged view of the interface shown in circle 6 of FIG. 2.

FIG. 7 is an enlarged view of the connecting portions shown in circle 7of FIG. 2.

FIG. 8 is a front elevational view of another seal device constructed inaccordance with the present invention.

FIG. 9 is a partial cross sectional side view of the seal device of FIG.8, taken along line 9--9 of FIG. 8.

FIG. 10 is an enlarged view of a portion of FIG. 9.

FIG. 11 is another enlarged view like FIG. 10.

FIG. 12 is a partial rear elevational view of the rotor member for theseal device of FIG. 8.

FIG. 13 is a partial cross sectional view of another seal deviceconstructed in accordance with the present invention.

FIG. 14 is a partial cross sectional view of the rotor member for theseal device of FIG. 13.

FIG. 15 is a partial cross sectional view of the stator member for theseal device of FIG. 13.

FIG. 16 is a partial cross sectional view of another seal deviceconstructed in accordance with the present invention.

FIG. 17 is a partial cross sectional view of the rotor member for theseal device of FIG. 16.

FIG. 18 is a partial cross sectional view of the stator member for theseal device of FIG. 16.

FIG. 19 is a partial cross sectional view of another seal deviceconstructed in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals indicatelike elements, there is shown in FIGS. 1-7 a ring-shaped seal device 10constructed in accordance with a first embodiment of the presentinvention The seal device 10 includes a stator member 12 and a rotormember 14 (FIG. 2). An O-ring 16 is provided between the stator member12 and a housing 18 (FIG. 3), and an O-ring 20 is provided between therotor member 14 and a shaft 22. The ring-shaped stator and rotor members12, 14 may be made of a suitable metal. In a preferred embodiment of theinvention, the stator and rotor members 12, 14 may be made ofpolytetrafluoroethylene (PTFE) or PTFE alloy. The O-rings 16, 20 may bemade of a suitable elastomeric material.

The stator O-ring 16 provides a tight seal between the stator member 12and the housing 18. Moreover, the radial compression of the O-ring 16between the stator member 12 and the housing 18 is sufficient to preventthe stator member 12 from rotating with respect to the housing 18. Therotor O-ring 20 provides a tight seal between the rotor member 14 andthe shaft 22, and the compression of the O-ring 20 between the rotormember 14 and the shaft 22 is sufficient to make the rotor member 14rotate in unison with the shaft 22.

In operation, the stator O-ring 16 prevents oil from escaping out of thehousing 18 around the outside of the stator member 12, and the rotorO-ring 20 prevents contaminants from traveling into the housing 18 alongthe surface of the shaft 22. Oil and contaminants are dynamicallyprevented from traveling in a radial direction through the interfacebetween the two ring-shaped members 12, 14 as explained in more detailbelow.

Since the stator member 12 does not rotate with respect to the housing18, the stator O-ring 16 is not subjected to friction. Therefore, thestator O-ring 16 has a long useful life. Similarly, since the rotormember 14 does not rotate with respect to the shaft 22, the rotor O-ring20 is not subjected to friction and has a long useful life.

The stator O-ring 16 is located within an annular recess 24. Asillustrated in FIG. 3, the recess 24 has a rectangular cross section.The rotor O-ring 20 is also located within a rectangular cross sectionedannular recess 26. The purpose of the recesses 24, 26 is to ensure thatthe O-rings 16, 20 are located in their proper positions when the sealdevice 10 is installed within the housing 18 to provide a seal aroundthe shaft 22.

For clarity of illustration, the O-rings 16, 20 are not shown in FIGS. 1and 4.

Referring to FIG. 2, the stator member 12 has a series of alternatingannular ridges 28, 30, 32 and annular grooves 34, 36. The grooves 34, 36are located between the ridges 28, 30, 32. An axial groove 38 isprovided at the bottom of the seal device 10 to connect the grooves 34,36 to the interior of the housing 18.

In operation, lubricating oil traveling outwardly along the surface ofthe shaft 22 past the first ridge 28 is rotated by the rotating shaft 22and thrown by centrifugal force into the first annular groove 34. Theoil then falls by gravity into the axial groove 38 and is therebydirected back into the housing 18. Oil that makes its way past the firstgroove 34 and past the second ridge 30 is thrown by centrifugal forceinto the second groove 36 and then drained by gravity into the axialgroove 38 to be directed back into the housing 18. Thus, the statormember 12 and the rotating shaft 22 work together dynamically to preventoil from escaping out of the housing 18. Essentially no oil escapesoutwardly past the second groove 36 and the third ridge 32.

The stator member 12 has an inwardly directed shoulder face 40 forcontacting an outer wall 42 of the housing 18 (FIG. 3). The shoulderface 40 is used during assembly to properly locate the stator member 12with respect to the housing 18. That is, the stator member 12 may besimply pushed into the housing 18 until the shoulder face 40 abutsagainst the housing wall 42. The shoulder face 40 prevents the statormember 12 from moving too far into the housing 18. The shoulder face 40may be omitted in an alternative embodiment of the invention. Spacelimitations may prevent the use of the shoulder face 40.

The stator member 12 also has a ring-shaped cover 44. The cover 44extends axially outwardly from the shoulder face 40. The cover 44 atleast partially surrounds the outside diameter of the rotor member 14.The cover 44 has an outwardly directed end face 46 that is coplanar withan outwardly directed end face 48 of the rotor member 14. The cover 44has a radial slot-shaped opening 50. The opening 50 is located at thebottom of the seal device 10 (like the axial drain groove 38 of thestator member 12). The cover opening 50 is used to direct contaminantsout of the seal device 10, as described in more detail below.

Referring to FIG. 6, the rotor member 14 has an inwardly directed face52 adjacent to an outwardly directed face 54 of the stator member 12.The two faces 52, 54 are spaced apart from each other such that there isessentially no friction between the two faces 52, 54. But the axialdistance S1 between the two faces 52, 54 is very small. The distance S1should be very small to prevent particles from traveling in a radiallyinward direction (i.e., toward the shaft 22) between the two faces 52,54. If the stator and rotor members 12, 14 are made of PTFE alloy, oranother suitable material, then the faces 52, 54 may lightly touch eachother.

As illustrated in FIG. 2, alternating annular ridges 56, 58, 60 andrecesses 62, 64 are located between the opposite end faces 52, 48 of therotor member 14. In the illustrated embodiment of the invention, theinner recess 62 is deeper than the outer recess 64. In an alternativeembodiment of the invention, the recess 64 may be deeper than the innerrecess 62. The purpose of the alternating ridges 56, 58, 60 and recesses62, 64 is to prevent contaminants from traveling toward the interior ofthe housing 18 and reaching the inwardly directed end face 52 of therotor member 14, as described in more detail below.

In operation, contaminants that find their way into the space betweenthe cover 44 and the rotor member 14 come into contact with the surfacesof the rotor recesses 62, 64. The rotation of the rotor member 14 causesthe contaminants to be thrown by centrifugal force onto the inner wall66 of the cover 44. The contaminants then move by gravity though theslot-shaped opening 50.

The stator member 12 and the rotor member 14 are connected together byconnecting portions shown in circle 7 of FIG. 2. As illustrated indetail in FIG. 7, the cover 44 has an inner annular recess 68 and therotor member 14 has a radially outwardly extending annular protrusion70. The recess 68 is located close to the outwardly directed end face 46of the cover 44. The recess 68 has a rectangular cross section with anoutwardly directed side face 72, an inwardly directed side face 74, anda cylindrical outer surface 76. The protrusion 70 may have a slantedsurface 78 for guiding the rotor member 14 into the cover 44. Theprotrusion 70 also has an outwardly directed side face 80 designed to bein close proximity to the inwardly directed side face 74 of the statormember 12. The axial distance between the side face 80 of the protrusion70 and the inwardly directed side face 74 of the recess 68 is designatedby reference character S₂.

It is advantageous to minimize the sum of the axial distances S₁ and S₂(FIGS. 6 and 7). This sum will be referred to herein as the total axialplay S_(t) of the seal device 10 (S_(t) =S₁ +S₂) In particular, thetotal axial play S_(t) should be as small as possible without beingequal to zero. When the axial play S_(t) is very small, there is verylittle room for contaminants to move in a radial direction through theinterface between the rotor member 14 and the stator member 12 (i.e.,between the end faces 52, 54. The rotor member 14 should fit within thestator member 12 with just enough play S_(t) to ensure that there issubstantially no friction between the relatively rotating members 12,14.

To assemble the seal device 10, the stator member 12 (including thecover 44), is expanded to increase the diameter of the cylindrical innersurface 66 of the cover 44 relative to the diameter of the protrusion70. In a preferred embodiment of the invention, the cover 44 is expandeduntil the diameter of the inner surface 66 is substantially equal to orgreater than the diameter of the protrusion 70 at its outer end region82. The rotor member 14 can then be easily moved axially into positionwithin the stator member 12, with the protrusion 70 located directlyradially inside of the recess 68. The stator member 12 is then allowedto return substantially to its original size such that the protrusion 70is located within the recess 68 as illustrated in FIG. 7. In a preferredembodiment of the invention, the inner surface 66 of the cover 44 isexpanded by heating the cover 44.

The above-described expansion technique is advantageous because it makesit possible to minimize the total axial play S_(t). If the protrusion 70were forced into the recess 68, by driving the rotor member 14 into thecover 44 without first expanding the cover 44, the radially outermostsurface 82 of the protrusion 70 would be temporarily distortedoutwardly. That is, the protrusion's side face 80 would be bentoutwardly, increasing the axial distance between the outer end region 82and the rotor member's inwardly directed side face 52. To provide roomfor this distortion during assembly, the total axial play S_(t) wouldhave to be increased, which would disadvantageously provide more roombetween the seal members 12, 14 for contaminants to travel into thehousing 18. The present invention overcomes this problem by reducing oreliminating axial resilient distortion of the protrusion 70 duringassembly

In the embodiment illustrated in FIGS. 1-7, particularly satisfactoryresults are achieved when the diameter of the shaft 22 is approximatelyone and one-eighth inches, the diameter of the opening of the housing 18receiving the stator member 12 is approximately two inches, and thetotal axial play S_(t) of the device 10 is approximatelyfour-thousandths of an inch. But the present invention is not limited tothese particular dimensions.

Another seal device 100 constructed in accordance with the presentinvention is illustrated in FIGS. 8-12. The seal device 100 isring-shaped and has a stator member 102, a cover member 104 connected tothe stator member 102, and a rotor member 106 located between the statormember 102 and the cover member 104. The ring-shaped members 102, 104,106 may be constructed of any suitable material, such as metal or PTFEalloy.

As illustrated in FIG. 9, the stator member 102 has alternating ridges28, 30, 32 and grooves 34, 36 and an axial groove 38 constructedessentially like those of the stator member 12 illustrated in FIGS. 1-7.But in contrast to the stator member 12, the stator member 102 also hasadditional axial grooves 108, 110, 112, 114, 116, 118, 120 (FIG. 8)connecting the annular grooves 34, 36 to the interior of the housing 18.Therefore, the stator member 102 is easier to install than the statormember 12, because the seal device 100 will perform satisfactorily withany one of the axial grooves 38, 108, 110, 112, 114, 116, 118, 120located near the bottom of the seal device 100. The seal device 100 willperform satisfactorily with any one of the axial grooves 38, 108, 110,112, 114, 116, 118, 120 located at the bottom of the seal device 100.

O-rings 122, 124 (FIG. 9) are provided for sealing the periphery of thestator member 102 to the housing 18 and for preventing the stator member102 from rotating O-rings 126, 128 seal the rotor member 106 to theshaft 22 and prevent the rotor member 106 from rotating relative to theshaft 22. The O-rings 122, 124, 126, 128 are constructed and operatelike the O-rings 16, 20 shown in FIGS. 2 and 3. For clarity ofillustration, the O-rings 122, 124, 126, 128 are not shown in FIGS. 8and 12. In alternative embodiments of the invention, one O-ring or morethan two O-rings may be used for each of the members 102, 106.

Referring to FIG. 10, the stator member 102 has an outwardly directedshoulder 130, a cylindrical axially extending member 132, a cylindricalrecess 134, and an annular face 136. Similarly, the cover member 104 hasan inwardly directed shoulder 138, a cylindrical inwardly extendingmember 140, a cylindrical recess 142, and an annular face 144. Theinwardly directed face region 138, 140, 142, 144 of the cover member 104is essentially a mirror image of the outwardly directed face region 130,132, 134, 136 of the stator member 102.

The rotor member 106 has a base portion 146 that fits between theshoulders 130, 138 of the stator and cover members 102, 104. The rotormember 106 also has a waisted section 148 for receiving the axiallyextending members 132, 140. Branched portions 150, 152 fit within therespective recesses 134, 142. An annular slot 154 is provided betweentwo radially outwardly extending annular elements 156, 158, locatedbetween the annular faces 136, 144 of the ring-shaped stator and covermembers 102, 104.

In an alternative embodiment of the invention, the inwardly directedbranched portion 150 may have an increased radial dimension, with aradially outer cylindrical surface aligned with the periphery of theoutwardly extending annular elements 156, 158. In the alternativeembodiment, there would be no inwardly directed annular face 136.

In the illustrated embodiment, to prevent contaminants from travelinginto the housing 18 and to provide for stable frictionless rotation ofthe rotor member 106 relative to the stator member 102, the axial lengthof the base portion 146 (measured in the direction of the axis of theshaft 22) is only slightly less (e.g., four-thousandths of an inch less)than the distance between the shoulders 130, 138, and the axial distancebetween the ends of the branched portions 150, 152 is only slightly less(e.g., four-thousandths of an inch less) than the distance between theradially extending surfaces 160, 162 of the cylindrical recesses 134,142.

Particularly advantageous results are achieved when the diameter of theopening for the housing 18 receiving the stator member 102 isapproximately two inches, the diameter of the rotating shaft 22 isapproximately one and one-sixteenth inches, the radial clearancesdesignated by reference characters r₁, r₂ and r₃ in FIG. 11 are eachapproximately two-hundredths of an inch, and the radial clearancesdesignated by reference characters r₄, r₅ and r₆ are each approximatelyone-hundredth of an inch. But the present invention is not limited tothese particular dimensions.

In operation, contaminants that reach the radially extending interfacesbetween the branched portions 150, 152 (FIG. 10) and the surfaces 160,162 of the annular recesses 134, 142 are rotated by the rotor member 106and are thereby caused to move radially outwardly (i.e., away from theshaft 22). Contaminants located between the stator member 102 and theinwardly directed branched portion 150 are moved by centrifugal forceinto the space located radially outwardly of the rotor member 106 (i.e.,in the vicinity of the annular slot 154 and radially inside of anannular ledge 164). Contaminants located between the cover member 104and the outwardly directed branched portion 152 are directed out of thedevice 100 through axial passageways 166 (only one of which is shown inthe drawings)

The passageways 166 may be equally spaced apart from each other andequidistantly spaced from the shaft 22. The passageways 166 may besufficiently close to each other that one of the passageways 166 isalways available for draining contaminants out of the cover member 104by gravity regardless of the orientation of the device 100. In theillustrated embodiment, there are eight passageways 166. But theadvantages of the invention may be achieved with more or lesspassageways. In the illustrated embodiment, the diameters of thepassageways 166 are each approximately six-hundredths of an inch. Butthe advantages of the invention may be achieved with larger or smallerpassageways.

The cover member 104 is connected to the stator member 102 by connectingportions that are constructed essentially like the connecting portions44, 68, 70, 14 illustrated in detail in FIG. 7. The connecting portionsare connected together by first increasing the diameter of the covermember 104 (e.g., by heating the cover member 104), then inserting thestator member 102 into the cover member 104 with the rotor member 106 inposition between the stator and cover members 102, 104, and thenreducing the diameter of the cover member 104 (e.g., by cooling thecover member 104) such that the protrusion 70 fits snugly within therecess 68. In the illustrated embodiment of the invention, connection ofthe cover member 104 to the stator member 102 is achieved with reducedor eliminated axial deformation of the protrusion 70 relative to therecess 68.

The above-described relative expansion technique makes it possible tominimize the separation between a ledge receiving face 170 and the end172 of the ledge 164, and to minimize the separation between therespective shoulder faces 174, 176 of the stator and cover members 102,104, such that the stator and cover members 102, 104 fit tightlytogether. The fit between the stator and cover members 102, 104 shouldpreferably be so tight that the cover member 104 is not movable withrespect to the stator member 102. Ideally, there is essentially noseparation between the ledge receiving face 170 and the ledge end 172,essentially no separation between the shoulder faces 174, 176, andessentially no separation between the inwardly directed face of theprotrusion 70 and the outwardly directed face of the annular recess 68.

Another seal device 200 constructed in accordance with the presentinvention is illustrated in FIGS. 13-15. The seal device 200 isring-shaped and has a stator member 202 and a rotor member 204. As inthe above-described embodiments, an O-ring 16 is provided between thestator member 202 and the housing 18, and an O-ring 20 is providedbetween the rotor member 204 and a shaft 22. For clarity ofillustration, the housing 18 and the shaft 22 are not shown in FIGS.13-15. The ring-shaped stator and rotor members 202, 204 may be made ofthe same materials as the stator and rotor members 12, 14 of theembodiment illustrated in FIGS. 1-7.

The operation of the embodiment illustrated in FIGS. 13-15 is similar tothe operation of the embodiment illustrated in FIGS. 1-7. The statorO-ring 16 prevents oil from escaping out of the housing 18 around theoutside of the stator member 202, and the rotor O-ring 20 preventscontaminants from travelling into the housing 18 along the surface ofthe shaft 22. Oil and contaminants are dynamically prevented fromtravelling in a radial direction through the interface between the tworing-shaped members 202, 204.

The stator O-ring 16 for the embodiment illustrated in FIGS. 13-15 islocated within an annular recess 224. As illustrated in FIG. 15, therecess 224 has a generally rectangular cross-section with sidewalls 225and 226 that diverge slightly away from each other in the radialdirection. In a preferred embodiment of the invention, the divergence227 of the sidewalls 225 and 226 from radial planes is approximately 5°.The diverging walls 225 and 226 make it easier to install and operatethe seal device 200. The recess 224 may be used with the seal devices10, 100 described above. The O-ring 20 is located in a recess 228 (FIG.14) that is similar to the recess 224 in that it has diverging sidewalls229, 230.

For clarity of illustration, the O-rings 16, 20 are not shown in FIGS.14 and 15.

Referring to FIG. 15, the stator member 202 has a series of alternatingannular ridges 28, 30, 32 and annular grooves 34, 36 for dynamicallypreventing oil from escaping out of the housing 18. As in the firstembodiment, essentially no oil escapes outwardly past the second groove36 and the third ridge 32.

The stator member 202 also has a ring-shaped cover 244. The cover 244extends axially outwardly from the shoulder face 40, similarly to thecover 44 of the first embodiment. The cover 244 at least partiallysurrounds the outside diameter of the rotor member 204.

An important difference between the embodiment illustrated in FIGS. 1-7and the embodiment illustrated in FIGS. 13-15 is that the rotor member204 for the latter embodiment has an annular notch 250 (FIG. 14) locatedin its outwardly directed end face 248. The cover 244 (FIG. 15) has aradially inwardly directed annular tooth 252 which fits into the notch250 to maintain the rotor member 204 in position during use. Thedimensions of the seal device 200 are such that the total axial play(i.e., the sum of the distance between the inwardly and outwardlydirected faces 52, 54 and the axial spacing between the side face 254 ofthe notch 250 and the side face 256 of the annular tooth 252 is verysmall, to prevent particles from travelling in a radially inwardlydirection (i.e., toward the shaft 22) between the two faces 52, 54.

As illustrated in FIG. 15, the stator member 202 has an offset portion270 which surrounds the interface between the faces 52, 54, and whichthereby increases the effectiveness of the seal device 200.

To assemble the seal device 200, the stator member 202 (including thecover 244) is expanded to increase the diameter of the radially innersurface 258 of the annular tooth 252 relative to the radially outersurface 260 of the rotor member 204. In a preferred embodiment of theinvention, the cover 244 is expanded until the diameter of the innertooth surface 258 is substantially equal to or greater than the diameterof the outer rotor member surface 260. The rotor member 204 can then beeasily moved axially into position Within the stator member 202, withthe annular tooth 252 fitting snugly within the annular notch 250.

Another seal device 300 constructed in accordance with the presentinvention is illustrated in FIGS. 16-18. The seal device 300 includes astator member 312 and a rotor member 314. In an assembled condition, anO-ring 16 is provided between the stator member 212 and the housing 18,and an O-ring 20 is provided between the rotor member 314 and the shaft22. The O-rings 16, 20 are located within recesses 224, 228, similarlyto the embodiment illustrated in FIGS. 13-15. The ring-shaped stator androtor members 312, 314 may be formed of the same materials as in theembodiments described above. The overall operation of the seal device300 is similar to the operation of the embodiments illustrated in FIGS.1-7 and 13-17.

The stator member 312 has a ring-shaped cover 344 extending axiallyoutwardly from a shoulder face 40. The cover 344 at least partiallysurrounds the outside diameter of the rotor member 314. The cover 344has a radial opening 340 located at the bottom for directingcontaminants out of the seal device 300, as in the above-describedembodiments.

In the embodiment illustrated in FIGS. 16-18, the cover 344 is shorterthan the rotor member 314. The rotor member 314 has an outwardlydirected end face 348 with a diameter that is substantially equal to thediameter of the stator member 312. An intermediate portion 352 extendsradially outwardly to an enclosure member 354. The enclosure member 354at least partially surrounds the cover 344 when the seal device 300 isassembled. The enclosure member 354 has an inwardly directed end face356 that fits snugly against an outwardly directed flange face 358 ofthe cover 344.

An annular tooth 360 (FIG. 17) is located on the radially inner surface362 of the enclosure member 354. The annular tooth 360 fits within arecess 364 (FIG. 18) located in the radially outer surface of the cover344.

To assemble the seal device 300, the rotor member 314 (including theenclosure member 354) is expanded to increase the diameter of the innersurface 366 of the annular tooth 360 (FIG. 17). By expanding the innertooth surface 366, the rotor member 314 can be moved into position withthe relatively rotatable faces 52, 54 directly adjacent each other, andthe enclosure member 354 may then be cooled or otherwise allowed toreturn substantially to its original size.

In the embodiment illustrated in FIGS. 16-18, the total axial play S_(t)would be equal to the sum of the distance between the faces 52, 54 andthe distance between the inwardly directed side face 368 of the recess364 and the outwardly directed side face 370 of the annular tooth 360.By minimizing the total axial play S_(t), there is very little room forcontaminants to move in a radial direction through the interface betweenthe rotor member 314 and the stator member 312. The rotor member 314should fit together with the stator member 312 with just enough playS_(t) to ensure that there is substantially no friction between therelatively rotating members 312, 314. If the members 312, 314 are formedof an appropriate material such as PTFE alloy, the total axial playS_(t) may be such that the end faces 52, 54 of the relatively rotatingmembers 314, 312 come into contact with each other.

Another seal device 400 constructed in accordance with the presentinvention is illustrated in FIG. 19. The seal device 400 is similar instructure and function to the seal device 200 illustrated in FIG. 13.However, the rotor member 404 for the seal device 400 has a cover flange406 with an outer diameter that is greater than the outer diameter ofthe outer rotor member surface 260. The cover flange 406 helps preventmaterial from moving into the space between the cover 244 and the outerrotor member surface 260. Another important difference between the sealdevice 400 and the seal device 200 is that the seal device 400 does nothave an offset portion 270 surrounding the interface between the faces52, 54. For clarity of illustration, the O-rings 16, 20 are notillustrated in FIG. 19. In operation, the O-rings 16, 20 would belocated in the respective recesses 224, 228, as in the embodimentillustrated in FIG. 13.

The above description is intended to be illustrative of preferredembodiments which can achieve the objects, features and advantages ofthe present invention It is not intended that the present invention belimited thereto. Any modifications coming within the spirit and scope ofthe following claims are to be considered part of the present invention.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A method of assembling a seal device, saidmethod comprising the steps of:providing a first ring member having aconnecting portion; providing a second ring member having a connectingportion; heating said connecting portion of said first ring member;subsequently, positioning said connecting portions such that saidconnecting portion of said second ring member is located radially insideof said connecting portion of said first ring member; and subsequently,cooling said connecting portion of said first ring member, and therebyconnecting said first and second ring members together; and wherein saidconnecting portions include a recess and a protrusion, and wherein saidconnecting step includes the step of locating said protrusion withinsaid recess; and wherein said connecting step includes the step ofrotatably connecting said first and second ring members together. suchthat said recess and said protrusion are rotatable relative to eachother subsequent to said connecting step.
 2. A method of assembling aseal device, said method comprising the steps of:providing a first ringmember having a connecting portion; providing a second ring memberhaving a connecting portion; heating said connecting portion of saidfirst ring member; subsequently, positioning said connecting portionssuch that said connecting portion of said second ring member is locatedradially inside of said connecting portion of said first ring member;and subsequently, cooling said connecting portion of said first ringmember, and thereby connecting said first and second ring memberstogether; and wherein said connecting portion of said first ring memberincludes an annular recess, and wherein said connecting portion of saidsecond ring member includes an annular protrusion, and wherein saidconnecting step includes the step of locating said annular protrusionwithin said recess.
 3. The method of claim 2, wherein said annularprotrusion has a slanted surface, and wherein said step of positioningsaid connecting portions includes the step of using said slanted surfaceto guide said second ring member into said first ring member.
 4. Themethod of claim 3, wherein said first ring member includes a radiallyinwardly directed substantially cylindrical surface, said annular recessbeing located within said radially inwardly directed surface, andwherein said annular protrusion has an annular outer end region, saidstep of heating said connecting portion including the step of increasingthe diameter of said radially inwardly directed surface until thediameter of said radially inwardly directed surface is equal to orgreater than the diameter of said annular outer end region of saidannular protrusion.
 5. The method of claim 4, wherein said first ringmember includes an annular ridge, an annular groove, an outwardlydirected face, an annular cover, and an axial groove for directinglubricant back into a housing, said cover having an opening fordirecting contaminants radially out of said first ring member, saidsecond ring member including an annular recess for preventingcontaminants from reaching said outwardly directed face of said firstring member, and wherein said method includes the step of positioningsaid second ring member radially inside of said annular cover.
 6. Themethod of claim 3, further comprising the steps of providing a thirdring member and locating said third ring member between said first andsecond ring members.
 7. The method of claim 6, wherein said second ringmember includes a shoulder face for positioning said second ring memberwith respect to a housing, said shoulder face being adjacent to saidannular protrusion.
 8. The method of claim 1, wherein said recess is anannular recess, said protrusion being an annular protrusion.
 9. Themethod of claim 2, wherein said connecting step includes the step ofrotatably connecting said first and second ring members together, suchthat said ring members are rotatable relative to each other subsequentto said connecting step.